1. Field of the Invention
This invention relates to a method of controlling foam in the processing and/or production of foodstuffs and in fermentation processes such as in the production of pharmaceuticals. More specifically, this invention relates to a method of controlling foam in the processing and/or production of foodstuffs and in fermentation processes such as in the production of pharmaceuticals through the use of terminally blocked polyethoxylated fatty alcohols.
2. Description of the Related Art
Foam control is of considerable importance in the sugar and yeast industry, in the potato processing industry, and in industrial fermentation processes such as those carried out on a commercial scale as in the production of antibiotics. In the commercial processing of, for example, sugar-containing saps such as occurs in the processing of sugar beets and sugar cane and in the manufacture of baker's yeast using molasses, or in the production of finished potato products such as french fries or potato chips, the formation of foam must be reduced to an amount that is harmless to the production process by the addition of anti-foam additives. A variety of surface active compounds are present in the saps involved in the production and processing of foodstuffs or in fermentation processes. These include naturally occurring substances such as humic acids, proteins, degradation products of proteins and starch, pectins, and saponins. These surface active materials contribute to the generation of unwanted foam which can occupy a considerable portion of the working volume of process vessels and therefore, effectively reduce the size of these vessels and ultimately lower the overall output of a particular production plant. In addition, a considerable amount of finished product can be lost if it is necessary to physically remove the foam in order to continue operating the process. Foam problems can be particularly acute in sugar refineries due to excessive foam generation in the diffusers, in the clarifiers, in the carbonizing tanks, and in the evaporators. In the fermentation vats involved in the manufacture of yeast a certain amount of foam has to be taken into account due to the ventilation of the fermentation broth, its extent however, must be confined to a certain limit. However, foaming is still a problem in fermentation processes. The foam controlling agents that are usually added to reduce the amount of foam generated in the production and processing of foodstuffs or in fermentation processes must be removed to a large extent from the solutions to which they have been added in order that the finished products are not impaired by the residual amounts of foam controlling agents.
One of the principal disadvantages of the prior art processes for controlling the generation of unwanted foams formed during the production and/or processing of foodstuffs or in fermentation processes lies in the fact that the anti-foaming agents have to be used in large quantities. Therefore, since they cannot be removed from process streams to the desired extent, the finished products are contaminated with the anti-foaming agents thereby causing potential odor and taste problems. In addition, since the anti-foaming agents also persist in the process streams and since these streams are normally disposed of directly to sewers, the anti-foaming agents should be biodegradable by the normal sewage treatment microorganisms. Also, anti-foaming agents used in fermentation processes such as in the manufacture of yeast must not impair the growth of the yeast cells and therefore, affect the yield of yeast from the fermentation process.
It is also important that anti-foaming agents used in food processing and fermentation operations maintain their effectiveness for long time periods. Some anti-foaming agents are effective only for short time periods after they are added requiring that repeated and costly additions be made in order to maintain an anti-foaming effect.
Prior art processes for controlling foam in food processing and fermentation operations include adding to the processing liquids a foam-controlling amount of for example, rape oil, peanut oil, olive oil, wool fat, fatty acid monoglycerides, fatty acid polyglycol esters, polyalkylene glycols, tall oil esters, ethylene oxide adducts of alkyl phosphoric acids, ethylene oxide adducts of branched fatty alcohols, alkylene oxide adducts of oligosaccharides, and free fatty alcohols. These types of compounds have not been effective foam-controlling agents because they must be used in relatively large amounts, or are not sufficiently biodegradable to meet current biodegradability standards. Rapid biological degradation without the formation of metabolites in the clarifying plant of a sugar refinery for example, is one of the most important requirements for foam-controlling agents today.
Some of the compounds employed as anti-foaming agents in the process of the present invention have been disclosed as components in foam-inhibiting compositions for cleaning meta glass, ceramic, or plastic in U.S. Pat. No. 4,548,729 (equivalent to European Patent Application No. EP-A-124815). The patent discloses a foam-inhibiting composition consisting of a terminally blocked polyethoxylated fatty alcohol of the general formula R--O--(CH.sub.2 CH.sub.2 O).sub.n --R.sup.1, wherein R is an alkyl or alkenyl group having from 8 to 18 carbon atoms, R.sub.1 is an alkyl group having from 4 to 8 carbon atoms and, n is an integer from 7 to 12. These compounds were not previously known for use in compositions which relate to foam suppression in food production or processing or in fermentation processes. There is no suggestion in U.S. Pat. No. 4,548,729 that a terminally blocked polyethoxylated fatty alcohol would be odorless, tasteless, and harmless to humans and would not impair the growth of microorganisms.
It is therefore, an object of the present invention to overcome the disadvantages of the prior art by providing a process for controlling foam in a food production or processing operation or fermentation operation which employs anti-foaming additives effective at low concentrations for extended periods of time which are also odorless and tasteless and harmless to humans. It is also an object of the present invention to provide a process for controlling foam in a fermentation operation which employs anti-foaming additives which do not impair the growth of microorganisms produced in the fermentation operation. It is a further object of the present invention to provide a process for controlling foam in a food production or processing operation or fermentation operation which employs anti-foaming additives which are biodegrade without the formation of metabolites.